Incinerator and method of operating the same



Aug. l0, 1965 B. B. REILLY INCINERATOR AND METHOD OF OPERATING THE SAMEFiled June 6, 1965 INVENTOR.

BER TRA/W E. RE/LL Y A f orneys 3,199,474 EJCKNERATOR AND METHOD GFQPERAHNG THE SAME Bertram B. Reilly, 17 Briar Cliff Road, Pittsburgh 2,Pa. Filed .inne 6, 1963, Ser. No. 286,048 Claims. (Ci. iiD-8) Thisinvention relates to an incinerator and method for operating the same,and, more particularly, to an incinerator with means provided forcausing downdrafts of air through the grates intermittently with theproduction of updrafts.

The burning of refuse of municipalities presents many problems whichmust be resolved to effect economical land sanitary disposal of suchwaste. The combustion of refuse fuels is complicated by the seasonalvariation of the type of trash to be burned, and the moisture content ofthe material which changes Widely from day-to-day because of rain, forexample. Also, it may be appreciated that the moisture content of yardtrash such as grass and shrubbery trimmings differs materially from thatof discarded material for incineration during the winter months. In eachinstance it is important that the incinerator be capa-ble of burningeconomically the charge introduced, regardless of the range of moisturecontent of material to be treated.

In many plants it has become necessary to agitate manually the fuel bedor charge on the stoker grate to break up an undesirable insulatinglayer of ash and noncombustibles formed on the surface of the fuel bed.To achieve efiicient and complete combustion it has been contemplated toagitate the bed mechanically in order to expose layers of the bedbeneath its insulating .surface to the heat of the furnace for burning.These known methods and plants, however, have not been totallysuccessful in the accomplishment of economical and complete combustionof incinerator fuel.

The present invention overcomes the deficiencies of conventionalincinerator stokers by the concept of increasing the temperature ofrefuse material on the grates, and particularly the subsurface materialwhich is not eX- posed directly to radiation from the flames of theincinerator burners. By this concept the moisture content of theincinerator fuel is lowered and the temperature of the total quantity offuel on the grate is raised to the kindling point. Control of the fuelbed temperature is maintained to avoid heat destruction of the Stokergrates.

It is an object of this invention to provide a new and improvedincinerator.

Another object is the provision of an incinerator wherein downdrafts andupdrafts of air through the stolcer grate may lbe effected selectivelyand regulated for raising and controlling the temperatures of the fuelbed on the grate to assure complete and eiiicient combustion.

A further object of the present invention is to provide an incineratorwhereby material beds on grates may be temperature controlled to avoidoverheating of the grates.

Still another object is to provide an incinerator with a stoker havinggrate sections with individual windboxes and with means for transferringthe heated air within one windbox to another for more eiiicientcombustion of material carried on the grate section of such otherwindbox.

A complete understanding of the invention may be had from the followingdetailed description of a specific embodiment thereof when read inconjunction with the appended drawing wherein the single figure is alongitudinal sectional view of the incinerator.

There is shown in the drawing an incinerator of the general type shownin my Patent 2,983,234, granted May 9, 196i, but as here shown there isa grate structure generally designated numeral 11 which includes anupper Patented Aug. 10, 1965 grate section 12 and a lower grate section13 disposed to receive material discharged from the upper grate. Each ofthe grate sections may have mechanical conveying characteristics, forexample, a reciprocating type grate, so that refuse introduced into theincinerator 14 by a charging ram and gate assembly 15 discharges intothe incinerator combustion chamber Ztl and onto the upper grate section12 where it is slowly conveyed while burning to the lower grate section13 by which it is transported and unburned or unburnable residues arefinally dropped into a quench tank 17. A drag conveyor 18 is provided inthe tank for the removal of ash and noncombustibles `from the furnace.Exhaust gases from the furnace are directed through a scrubber 19 priorto vent- 'ing to the atmosphere from a stack not shown.

The grate sections 12 and 13 are arranged within the incineratorcombustion chamber Ztl of the furnace 14 such that the chamber isdivided by the grates longitudinally into two spaces, one above thegrate sections designated 29a and the other lying below the sections andindicated by numeral Ztib. The space Ztb is further divided intoindependent windboxes 21 and 22 which are defined by the grate sections12 and 13, respectively, and by baffle plates 23, 2d, and 2S which aresecured to and depend from the grate sections which bridge across thetops of the plates. The windboxes 21 and 22 are sealed across theirlower portions by a liquid 26 contained within the quench tank 17 whichis disposed beneath the gratos such that the baiiie plates 23, 24, and25 extend below the liquid surface 27. As thus constructed, dierentialpressures may be maintained under the grate sections covering therespective windboxes.

An air circulatory system 28 for forcing air selectively through thegrate sections 12 and 13 and the material thereon is shown to include afan 29 which forces combustion air from the atmosphere into a header 31.The header branches into a pipe 32, which opens into the windbox 21, andpipe 33, which opens into the windbox 22. A transfer conduit 34 isinterconnected to the pipe 33 at a point intermediate the fan 29 and thewindbox 22 and to the input of a transfer fan 35. The output of thelatter fan forces the air drawn through the conduit 34 onwardly into thewindbox 21 via a duct 3d.

For regulation of the tlow of air through the duct 36, pipe 33, and pipe32 dampers 37, 38, and 39, respectively, are positioned operatively inthe circulatory system 2S. The control of the dempers and the fanoperation is had by a conventional controller, not shown, or manually.As depicted, the damper 37 is normally closed when the damper 38 isopen, and the damper 39 is normally open when the damper 38 is open andthe damper 37 is closed. The dampers 37 and 38 are preferably sointerlocked such that -when updrafts of air `are introducedsimultaneously in both windboxes 21 and 22 by operation of the fan 29damper 37 is closed. However, when the transfer fan 35 is operated, adowndraft of heated air and gases is drawn from the combustion space 2daabove the grate through the grate section 13 and conveyed through theconduit 34 and the tube 3d to the windbox 21. At such time the damper 37is open and the damper 3S is closed so that combustion air from blower29 is forced only into the windbox 21. The fuel bed on the grate section12 is thus heated by the introduction of heated air and gases intowind-box 21 and forced upwardly with the air from blower 29 through thematerial on the grate section 12. This accelerates the driving off ofmoisture from the material not exposed to the radiation of the furnaceiiame and in raising the bed temperature under its surface. to thekindling point.

In normal operation with air blowing upwardly through both gratesections, the air cools the grates but when grate section 13 isoperating with downdraft, it may be- -to a lesser extent by the grate l2during the downdraft operation through grate 13 will be recuperated whenthe operation is reversed, the grates yielding their heat to the airbefore the air passes into the material above the grate.

The lower grate section 13 is the one selected in the vincinerator 14through which a downdraft of gases is caused to flow because it islcloser to the quench tank 17, and, since more ashes will be s-iftedfrom the grate section 13 into the tank by such downdrafts, it isdesirous to remove the sifted ash from the furnace .system without delayto maintain a cleaner exhaust gas.

It is manifest that the above-described embodiment of the invention ismerely illustrative and that numerous modifications may be made withoutdeparting from the spirit and scope of the invention.

What is claimed is:

1. An ineinerator comprising an enclosing furnace structure, alongitudinally extending grate in the structure with a combustionchamber `above the grate and an air space below the grate, a waterretaining quench trough extending under the grate and forming a bottomenclosure for the air space, bafiies extending downwardly from the grateinto the quench tank at spaced intervals dividing said space into atleast two separate chambers, means for selectively supplying combustionair under pressure to both of said two chambers, and means forselectively blocking the flow of air to one of said chambers and drawinggases downwardly from the combustion chamber through the grate into thesaid one chamber and delivering the gases so withdrawn into the otherchamber.

2. The method of incinerating rubbish which comprises discharging therubbish onto a grate along which the rubbish is progressively moved, andalternately flowing combustion air upwardly through substantially theentire length of the grate and then through only a rst portion of theentire length while simultaneously drawing gases from above the gratedownwardly through another portion and mixing the gases so withdrawnwith the air supplied to the first portion before the air supplied tothe first portion has moved upwardly through the grate.

3. An incinerator comprising a chamber; grates disposed within thechamber at different levels with material to be burned on each gratebeing discharged Ito a next lower grate; a tank forming the bottom ofthe chamber within which a liquid is a-dapted to be confined and intowhich ash sifted through each grate falls and the burned residue fromthe lowest grate discharged; bafile plates secured to each grate formingwalls with each grate il bridging the respective plates; the platesdepending into the tank below the top of the tank sufficiently to extendbelow the surface of the liquid adapted to be confined in the containerwhereby when liquid is placed in the tank to a level above the bot-tomedges of the baille plates the liquid surface, a grate, and therespective baffle plates define discrete windboxes; first means forintroducing air into each windbox to force an updraft through each grateand material thereon; second means for withdrawing gas from at least onewindbox of at least one grate for causing a downdraft of air and gasthrough the one grate and material thereon and for transferring thewithdrawn air and gas to another windbox under pressure while the firstmeans forces air into the other windbox; and third means for terminatingthe lintroduction of updraft air to the one windbox at the time saiddowns-f 'A draft of air and gas is being effected.

4. An incinerator comprising a furnace with a grate structure with acombustion space above the grate structure, a succession of at least twowindboxes under the grate designed to be operated at different relativepressures, means for selectively supplying air to both of said windboxesor selectively cutting off the air supply to one while supplying air tothe other, and means operable for withdrawing gases and air from thatbox which is cut off from said air supply and forcing it into the onereceiving the air supply whereby there is a down-draft flow of air andgases from the combustion chamber into the one so cut off from the airsupply and the downdraft gases are mingled with the air in the otherwind-box.

5. An incinerator having a furnace structure with a grate for receivingmaterial to be burned at one end and discharging ash from the other,there being a combustion space above the grate, a first windbox underthe grate extending from the receiving end part way toward the dischargeend, and a second windbox designed to be operated at a pressuredifferential relative to the first succeeding the first, means forselectively supplying combustion air to the rst and second windboxes orto only the first, and means effective when air is supplied only to thefirst for withdrawing air and gases from the second and discharging theminto the rst to generate a downdraft of heated air and gases from thecombustion charnber into the second windboX and accelerate the drying ofmaterial on the grate by the subsequent upflow thereof through the grateabove said rst windbox.

References Cited bythe Examiner UNITED STATES PATENTS 1,146,255 7/15Hock 110-72 3,057,308 10/62 Knipping 110-8 JAMES W. WESTHAVER, PrimaryExaminer.

JOHN I. CAMBY, Examiner.

2. THE METHOD OF INCINERATING RUBBISH WHICH COMPRISES DISCHARGING THERUBBISH ONTOA GRATE ALONG WHICH THE RUBBISH IS PROGRESSIVELY MOVED, ANDALTERNATELY FLOWING COMBUSTION AIR UPWADLY THROUGH SUBTANTIALLY THEENTIRE LENGTH OF THE GRATE AND THEN THROUGH ONLY A FIRST PORTION OF THEENTIRE LENGTH WHILE SIMULTANEOUSLY DRAWING GASES FROM ABOVE THE GRATEDOWNWARDLY THROUGH ANOTHER PORTION AND MIXING THE GASES SO WITHDRAWNWITH THE AIR SUPPLIED TO THE FIRST PORTION BEFORE THE AIR SUPPLIED TOTHE FIRST PORTION HAS MOVED UPWARDLY THROUGH THE GRATE.